首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   42862篇
  免费   4233篇
  国内免费   772篇
耳鼻咽喉   260篇
儿科学   1484篇
妇产科学   686篇
基础医学   3478篇
口腔科学   399篇
临床医学   5932篇
内科学   5812篇
皮肤病学   454篇
神经病学   1873篇
特种医学   949篇
外国民族医学   1篇
外科学   3323篇
综合类   3670篇
现状与发展   1篇
一般理论   5篇
预防医学   10489篇
眼科学   210篇
药学   6827篇
  51篇
中国医学   1050篇
肿瘤学   913篇
  2024年   127篇
  2023年   1023篇
  2022年   1949篇
  2021年   2703篇
  2020年   2272篇
  2019年   2076篇
  2018年   1995篇
  2017年   1927篇
  2016年   1893篇
  2015年   1902篇
  2014年   2947篇
  2013年   4024篇
  2012年   2588篇
  2011年   2562篇
  2010年   1963篇
  2009年   1825篇
  2008年   1782篇
  2007年   1715篇
  2006年   1443篇
  2005年   1224篇
  2004年   1014篇
  2003年   859篇
  2002年   691篇
  2001年   614篇
  2000年   502篇
  1999年   429篇
  1998年   420篇
  1997年   352篇
  1996年   347篇
  1995年   382篇
  1994年   257篇
  1993年   199篇
  1992年   240篇
  1991年   202篇
  1990年   178篇
  1989年   138篇
  1988年   167篇
  1987年   123篇
  1986年   120篇
  1985年   134篇
  1984年   110篇
  1983年   79篇
  1982年   71篇
  1981年   53篇
  1980年   54篇
  1979年   43篇
  1978年   49篇
  1977年   29篇
  1976年   20篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
本试验是在多种食品的基础上,加大照射剂量(吸收剂量为0.1~8.0 kGy)和提高辐照食品在膳食中比例(千重80%以上)的条件下,进行了150d的大白鼠喂养试验。通过对饲料的营养成分分析及其利用,对动物的生长发育、血液学、致突变性及病理学等项指标的检测,结果证明是安全的。本试验结果为今后辐照食品商业化提供了安全的证据。  相似文献   
132.
[目的 ]分析中药车前草中的无机盐成分 .[方法 ]利用正丁醇萃取、乙醇沉淀去杂质、聚酰胺柱层析及大孔吸附树脂柱层析等方法进行分离和提纯 .[结果 ]从车前草中分离得到 1种无机物 ,鉴定为氯化钾 .  相似文献   
133.
医院洁净手术室智能监控系统的设计与实现   总被引:1,自引:0,他引:1  
随着信息技术和自动化技术的发展,实现手术室的智能监控有助于提高工作效率和确保手术安全进行.本文简要介绍了"医院洁净手术室智能监控系统"的设计理念及其相关功能,给出了系统的硬件配置和软件实现.  相似文献   
134.
BACKGROUND: The process of gastro-duodenal digestion may play a role in determining the allergenic properties of food proteins. The sensitizing and allergenic potential of digestion products of highly degraded allergens, such as the major peanut allergen Ara h 1, is currently under debate. We evaluated the effect of in vitro gastro-duodenal digestion of Ara h 1 on T cell reactivity and basophil histamine release. METHODS: An in vitro model of gastro-duodenal digestion was used to investigate changes in the allergenic properties of Ara h 1 using in vitro assays monitoring T cell reactivity (proliferation, cytokine production) and histamine release of basophils from peanut allergic individuals. The digestion process was monitored using an SDS-PAGE gel. RESULTS: In vitro gastric digestion led to rapid degradation of Ara h 1 into small fragments M(r) L5600. Gastric digestion did not affect the ability of Ara h 1 to stimulate cellular proliferation. Gastro-duodenal digestion significantly reduced its ability to stimulate clonal expansion (P<0,05; Wilxocon's signed rank test). The Th-2 type cytokine polarization of T cells from peanut allergic donors (IFN-gamma/IL-13 ratio and IFN-gamma/IL-4 ratio of CFSE(low) CD4(+) T cells) remained unchanged regardless of the level of digestion. Histamine release of basophils from peanut allergic individuals was induced to the same extent by native Ara h 1 and its digestion products. CONCLUSION: Gastro-duodenal digestion fragments of Ara h 1 retain T cell stimulatory and IgE-binding and cross-linking properties of the intact protein.  相似文献   
135.
Objective. To quantify the relationship between utilization of care among the uninsured and the structure of the local health care market and safety net.
Data Sources/Study Setting. Nationally representative data from the 1996 to 2000 waves of the Medical Expenditure Panel Survey (MEPS) linked to data from multiple secondary sources.
Study Design. We separately analyze outpatient care utilization and whether an individual incurred any medical expenditure among uninsured adults living in urban and rural areas. Safety net measures include distances between each individual and the nearest safety net providers as well as a measure of capacity based on local government and hospital health expenditures. Other covariates include the managed care presence in the local health care market, the percentage of individuals who are uninsured in the area, and local primary care physician supply. We simulate utilization using standardized predictions.
Principal Findings. Distances between the rural uninsured and safety net providers are significantly associated with utilization. In urban areas, we find that the percentage of individuals in the area who are uninsured, the pervasiveness and competitiveness of managed care, the primary care physician supply, and safety net capacity have a significant relationship with health care utilization.
Conclusions. Facilitating transport to safety net providers and increasing the number of such providers are likely to increase utilization of care among the rural uninsured. Our findings for urban areas suggest that the uninsured living in areas where managed care presence is substantial, and especially where managed care competition is limited, could be a target for policies to improve the ability of the uninsured to obtain care. Policies oriented toward enhancing funding for the safety net and increasing the capacity of safety net providers are likely to be important to ensuring the urban uninsured are able to obtain health care.  相似文献   
136.
BACKGROUND: In 1998, the UK government issued precautionary advice that pregnant or breast-feeding women with a family history of atopy, may wish to avoid eating peanuts during pregnancy and lactation. This study aimed to assess the compliance with this recommendation and investigate its impact upon peanut sensitization. METHODS: A total of 858 children born immediately after the advice were followed for 2 years and assessed for peanut sensitization. A standardized questionnaire was used to ascertain history of atopy and maternal exposure to peanuts during pregnancy. Following parental consent children were skin prick tested to assess sensitization to peanuts. RESULTS: Sixty-five per cent of mothers had avoided peanuts during pregnancy. Forty-two per cent of the mothers had heard about the government advice, and half modified their diet as a consequence. Neither maternal nor family history of atopy had any significant effect on peanut consumption. Parity did play a role, and mothers having their first child were twice as likely to change their diet (P<0.001). Mothers of 77% of the children sensitized to peanuts had avoided peanuts during pregnancy. In this cohort study maternal consumption of peanut during pregnancy was not associated with peanut sensitization in the infant. CONCLUSIONS: The majority of mothers in this cohort avoided peanut consumption during pregnancy. It is likely that either the government advice is misunderstood by mothers, or that those who communicate the advice have not fully explained who it is targeted at.  相似文献   
137.
[目的]了解供机食品的卫生状况,分析鉴定目的菌的特性。[方法]依据相关国家标准及VITEK操作手册对病原微生物进行检验和鉴定。[结果]从1份供机食品-豇豆中同时检出屎肠球菌、坚韧肠球菌及大肠杆菌,分别具有这3种病原菌的典型培养特性、菌体特征及生化特性。[结论]日常工作中应重视对多种病原菌的检验及加强对供机食品从原料到成品的全过程卫生监控,以保障工作人员及乘客的生命安全。  相似文献   
138.
There are more than 40 H(1)-antihistamines available worldwide. Most of these medications have never been optimally studied in prospective, randomized, double-masked, placebo-controlled trials in children. The aim was to perform a long-term study of levocetirizine safety in young atopic children. In the randomized, double-masked Early Prevention of Asthma in Atopic Children Study, 510 atopic children who were age 12-24 months at entry received either levocetirizine 0.125 mg/kg or placebo twice daily for 18 months. Safety was assessed by: reporting of adverse events, numbers of children discontinuing the study because of adverse events, height and body mass measurements, assessment of developmental milestones, and hematology and biochemistry tests. The population evaluated for safety consisted of 255 children given levocetirizine and 255 children given placebo. The treatment groups were similar demographically, and with regard to number of children with: one or more adverse events (levocetirizine, 96.9%; placebo, 95.7%); serious adverse events (levocetirizine, 12.2%; placebo, 14.5%); medication-attributed adverse events (levocetirizine, 5.1%; placebo, 6.3%); and adverse events that led to permanent discontinuation of study medication (levocetirizine, 2.0%; placebo, 1.2%). The most frequent adverse events related to: upper respiratory tract infections, transient gastroenteritis symptoms, or exacerbations of allergic diseases. There were no significant differences between the treatment groups in height, mass, attainment of developmental milestones, and hematology and biochemistry tests. The long-term safety of levocetirizine has been confirmed in young atopic children.  相似文献   
139.
他达拉非治疗勃起功能障碍的安全性研究进展   总被引:2,自引:2,他引:0  
勃起功能障碍(erectile dysfunction,ED)是中老年人的常见疾病。他达拉非自2002年10月开始用于治疗ED,其疗效确切,安全性高,因此越来越多的患者选择他达拉非来治疗ED。目前对他达拉非的作用机制、药代动力学、疗效、安全性等方面已经有了较多的基础及临床研究资料。本文就他达拉非治疗ED的安全性做一综述,以求该药物在临床上得到更安全的使用,为临床医生选择使用该类药物提供参考。  相似文献   
140.
PURPOSE: To describe and discuss the status of patient safety in U.S. hospitals. METHODS: Personal interview. This report is part of a series of discussions with a leading expert on patient safety. FINDINGS AND CONCLUSIONS: Some improvements have been made in the past 10 years. But changes have not been adequate. Continuing barriers include the punitive environment in hospitals, physicians' denial of the scope of the problem, lack of national leadership, and lack of systems thinking.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号